Experts Call for Redefinition of 'Cancer'

TUESDAY, July 30 (HealthDay News) -- A panel of experts
commissioned by the U.S. National Cancer Institute says that the
word "cancer" may need to be redefined to prevent overdiagnosis and
overtreatment of conditions that are often not lethal.

Writing in the July 29 online edition of the
Journal of the American Medical Association, the experts say
that widespread cancer screening programs turn up too many growths
that would not progress to a lethal stage and are considered
"indolent."

Most patients do not understand that distinction, however, and
"the word 'cancer' often invokes the specter of an inexorably
lethal process," wrote Dr. Laura Esserman of the University of
California, San Francisco, Dr. Ian Thompson Jr. of the University
of Texas Health Science Center at San Antonio, and Dr. Brian Reid
of the Fred Hutchinson Cancer Research Institute in Seattle.

Cancer can take "multiple pathways," the three say, "not all of
which progress to metastases and death, and include indolent
disease that causes no harm during the patient's lifetime."

This re-examination of what constitutes a cancer diagnosis has
been spurred by the explosion over the past few decades of
sophisticated screening measures such as the mammogram, colonoscopy
and the PSA blood test (for prostate cancer). All were heralded as
potentially lifesaving, and many predicted that widespread adoption
of these tests would catch disease early and cause cancer rates to
fall.

But the cancer screening story has turned out differently, the
panel noted, because many of the lesions picked up on screening
have turned out to be indolent.

"Screening for breast cancer and prostate cancer appears to detect more cancers that are potentially clinically insignificant," the experts said. The same might be said for screens for thyroid cancers and melanomas -- certainly, lives have been saved because tumors were detected and treated, but "the detection of indolent disease" has risen, too, the panelists wrote.

Issues like this have played out in recent years. The United
States Preventive Services Task Force, an influential government
panel, caused a furor in 2009 when it called for the abandonment of
regular mammography screening for women under 50, reasoning that
the benefits of screening for younger women were outweighed by the
risks. The same panel also rejected the widespread use of the PSA
test, noting that it too often picked up slow-growing lesions that
might never harm men's health.

According to the experts writing in
JAMA, the best-case scenario for cancer screening is when
the tumor is slow-growing but also typically progressive. Colon
cancer often acts in this way, the team noted, and colonoscopy has
become an "effective" screening program.

In the meantime, however, "overdiagnosis" occurs. The experts
say a redefinition of cancer may be needed to quell patient fears
over indolent lesions and curb overdiagnosis and overtreatment.

"Use of the term 'cancer' should be reserved for describing lesions with a reasonable likelihood of lethal progression if left untreated," they wrote. Other growths would be classified in a lesser category, "indolent lesions of epithelial origin" (IDLE).

A change in mindset may also be needed for patients and health
care workers alike. "Physicians, patents and the general public
must recognize that overdiagnosis is common and occurs more
frequently with cancer screening," the team wrote.

The recommendations are sure to spur debate, but one outside
expert said that debate may be what is needed on this issue.

"We're still having trouble convincing people that the things that get found as a consequence of mammography and PSA testing and other screening devices are not always malignancies in the classical sense that will kill you," Dr. Harold Varmus, director of the National Cancer Institute, told The New York Times. "Just as the general public is catching up to this idea, there are scientists who are catching up, too."

But not everyone agrees. Dr. Larry Norton is medical director of
the Evelyn H. Lauder Breast Center at Memorial Sloan-Kettering
Cancer Center in New York City. He said the problem is that even
some relatively indolent breast growths, such as ductal carcinoma
in situ (DCIS), can go on to become progressive, lethal
cancers.

"Which cases of DCIS will turn into an aggressive cancer and which ones won't?" he told the Times. "I wish we knew that. We don't have very accurate ways of looking at tissue and looking at tumors under the microscope and knowing with great certainty that it is a slow-growing cancer."

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